#4 1.Corrected <opt>; 2.Added <sequence> element

[Jakub Holý]

1. I corrected the problem with <opt platform="xy">
which were not processed by ADOdb DataDict due to the
fact that they weren't stored under a key equal to the
target platform name (example: was: 0=>'my opt', is:
"mysql"=>'my opt') in the array passed to
CreateTableSQL - see the bug #1370289

2. I added the element <sequence name=..
initialValue=.. platform=.. drop=..> to be able to
define sequences in axmls. It cannot be handeled in the
same way as other elements because DataDict doesn't
support it and we must use directly ADOConnection to
generate them.

[Jakub Holý]

Corrected processing of OPT, added processing of SEQUENCE

[Jakub Holý]

axmls dtd with the sequence element and comments